Current GFS suggests mean CET would stay in the 15 to 15.5 range to about Saturday 19th then could slowly rise with the mean from 20th to 31st looking closer to 17.5 or 18. This would suggest an outcome of about 16 to 16.3 C.

I have recalculated the year to date CET means from weighted monthly values, a slight change from the simple average used in earlier tables. On that basis, 2017 is still running second behind 2014 and here's the top twelve, the number in brackets refers to position at end of full year.
1. 2014 __ 10.72 (1)
2. 2017 __ 10.57 (?)
3. 1846 __ 10.55 (31)
4. 1733 __ 10.54 (t-15)
5. 2007 __ 10.53 (t-15)
6. 1990 __ 10.50 (5)
7. 1834 __ 10.46 (t-13)
8. 1868 __ 10.45 (20)
9. 1686 __ 10.40 (32)
10. 1822 __ 10.39 (t-43)
t11. 1921 __10.38 (t-13)
t11. 1775 __10.38 (t-35)
_______________________________________________
These top twelve years generally lost a bit of ground although 2014 maintained top spot and 1990 held its position (it was 5th Jan to July before this year). Just one note, the Hadley site lists 10.51 as the CET to date, this does not match their own data so I can't explain that discrepancy. If you average the 212 days instead of using the weighted mean of months, it comes out to 10.56, and if you take the raw average of months (which they don't in their other work) it is still a bit higher than 10.51. Maybe they are applying a correction factor that they will later apply to the monthly data.

You may notice that the previous post appears twice. This is an indirect result of the wonky edit function on this site.
At least it is wonky for me. I spotted an error while I was posting a reply (a summary of long spells of wet weather from these tables). The error is corrected in post number two so any moderator feel free to remove the first of the two otherwise identical posts. If you want to verify that you are removing the right post, it will have a date of 1912 in late April, the corrected post has 2012 on that date. Readers should only use the second of the two posts if they are both visible. That will be the one immediately above this post.
Here's why that happened. The edit button was still visible in the post above my reply post. So I tried to edit it. When I pressed post on the edit, I got an error message so I went back to my reply, but that had changed to the edit of the post and my reply otherwise had vanished.
So I clicked on submit reply and at least got the edited version to post.
Anyway, this is what I was going to post ... there are numerous examples of consecutive entries in the 10-day wet intervals, making them essentially wet 14 to 20 day intervals. One of the longest, from late October 1940 to mid-November of 1940, was using 20 consecutive days and 11 consecutive intervals, but a slightly higher value in 2000 on one day in the series truncated that 20-day period. Another similar case was in Feb 1977 which used 20 consecutive days but failed to overcome one entry already in the table from 1951. The longest surviving interval without any interruption is 19 days, from 1 to 19 July 1968 (providing 10 to 19 July in the tables), and also from 31 March to 18 April 1998 (providing the maxima for April 9 to 18 in the table), also tied by 5 to 23 September 1994 (19 days) providing the maxima for 14 to 23 September in the table. The 18 day interval from 7 to 24 Dec 1989 is noteworthy because it contains the highest value in the table, 95.9 mm (11-20 Dec 1989). The wet June of 2007 provided an 18 day spell 8th to 25th June. Another 18 day interval was 3 to 20 August of 2004.
As to the historical frequency, this table indicates the number of days in each decade per month. Three days out of the 366 in the year had a tied value and these count for 0.5 in the frequency table below. Only the higher values from 1 to 9 March are counted.
It should be noted that since the entries in the table end on dates in various months, the frequencies refer to nine days from the previous month as well as all the days in the given month:
To compare the last entry (2011-17) to other decades, multiply by 1.5, as we are almost exactly two-thirds of the way through this decade. No entries were found for 2017 anyway.
Frequency ____ JAN _ FEB _ MAR _ APR _ MAY _ JUN _ JUL _ AUG _ SEP _ OCT _ NOV _ DEC __ TOTAL
1931-40 ______ 3 ____ 1 ____ 3 ____ 0 ____ 8 ____ 0 ___ 1 ____ 2 ___ 6 ___ 2 ___ 12 ____ 1 _____ 39
1941-50 ______ 7 ____ 4 ____ 9 ____ 0 ____ 0 ____ 0 ___ 0 ____ 1 ___ 0 ___ 7 ____ 5 ____ 0 _____ 33
1951-60 ______ 4 ____8.5 ___6.5 ___ 1 ____ 0 ____ 1 ___ 1 ____ 1 ___ 0 ___ 2 ____ 2 ____ 2 _____ 29
1961-70 ______ 0 ____ 0 ____ 5 ____ 0 ____ 8 ____ 0 ___15____ 5 ___ 3 ___ 0 ____ 0 ____ 5 _____ 41
1971-80 ______ 1 ___ 12.5 __ 0.5 ___ 3 ____ 5 ____ 3 ___ 4 ____ 5 ___ 3 ___ 7 ____ 0 ____ 9 _____ 53
1981-90 ______ 0 ____ 0 ____ 2 ___ 8.5 ____3 ____ 4 ___ 0 ____ 0 ___ 2 ___ 3 ____ 0 ____ 9 _____ 31.5
1991-2000 ____ 6 ____ 0 ____ 1 ___16.5 ___ 1 ____ 9 ___ 4 ____ 0 ___15 ___4 ____ 3 ____ 0 _____ 59.5
2001-10 ______10____ 2 ____ 1 ____ 0 ____ 5 ____10 ___6 ____17 ___1 ___ 6 ____ 1 ____ 1 _____ 60
2011-17 (Jul) ___0 ____1 ____ 3 ____ 1 ____ 1 ____ 3 ___ 0 ____ 0 ___ 0 ___ 0 ____ 7 ____ 4 _____ 20
The above analysis combined with some inspection of the data shows that long wet spells were less frequent from about 1941 to 1974 than from 1975 to 2012, but have become less frequent again since 2013.
The interval from 1998 to 2004 had a particularly high count, resumed in 2007 after two years that did not register.
The decade 1951-60, while generally not prolific, was active in the first quarter of the year.

I can't edit that above, but instead of making January and July the months with the extreme point, make them February and August with the extreme point maybe 0.1 lower than January by 10 February, and 0.2 higher than July by 07 August. Then start a regular increase after 10 Feb to the Feb mean, and a regular decrease in August to the August mean. January you can drop from the Dec mean to about the 25th then hold steady, and July you can increase slowly but pace it faster to the 25th.

Vizzy2004, you will find that the rolling averages for 1981-2010 contain some quirks that are created by the occasional unbalanced nature of the 30 years that go into the period, these are not real features of the climate and a longer average removes them (or damps them down to almost nothing).
So that being said and given the fact that your averages are probably based on a lot fewer years anyway, but including seven that are not in the baseline period, you can get the effect you want by estimating as follows:
First, take the cooling months (August to December) and start the rolling mean for each month on the value of the mean of the previous month. Then just take equal amounts per day through the cooling months. An example would be this, let's say your mean for September is 14.0 and for October 11.0, that's 3.0 deg of cooling and your running mean will work out to be 0.1 colder each day from 14.0 on 1st to 11.1 on 30th.
December you might find a better result if you let the drops go at a faster rate 1st to 20th then slow them down.
January and July are months with the instantaneous extremes within them, so for these, you start at the mean of the previous month, end with the mean for January or July, but somewhere between (25th would be my choice) you blend in a more extreme value by 0.2 deg (if your January mean is 4.4, then make that 4.2).
Then that leaves the five warming months of February to June, for these you just reverse the process, starting with 0.1 higher than the previous month on day one, and ending up with your monthly mean on day 30 or 31 at the end. And in general these months can have a steady rise, it will be pretty close to 0.1 each day although more like every other day in February.
That would save you all the work of looking up the rolling averages, and actually I think we should use those here because the values calculated from the data have those ups and downs that don't really tell us anything of a valid statistical nature, the 1961 to 1990 data used by the Met Office presumably have the same sort of quirks built in, I have never eyeballed the graphs of the two sets to find out if the quirks of each set have any relationship to those of the other set. If they do, and then they show up in similar data from the past, then maybe there's something significant about them, but if they are just random zigs and zags, they are probably just "noise" introduced by the fact that 30 years are not enough to smooth out the data to the point that 245 years will do.

The only place I know with the rolling averages for the 12 months (1981-2010) would be here in these threads when I post them along with record values. You would need to look at the last twelve contest threads to find these, and look around the 2nd of each month after most of the entries are in. I have already posted August values.

In the record daily rainfalls for July, 11th (10.5, 1953) has been replaced by 11.7 mm in 2017.
This was one of the lower July daily records.The only other July records this amount would have passed were on 4th, 5th, 19th and 23rd. The record for the previous day was 50.0 mm.

The only 16.9 person who needs a speech is Born From the Void, I list them in order of entries, the same way J10 scores them. So if 16.9 wins, the first entry is high score. If 17.0 wins, then it's Hammer, and if it's 16.8, it would be Weather 26.

Full table of entries now posted here:
https://www.netweather.tv/forum/topic/75427-cet-competition-the-scores-ongoing/?page=8
58 total entries, median still 16.5 C.
Trend on GFS is cool until 8th then warmer than average for most of the next 12 days to end of run, would estimate a minimum of 15.0 might be reached by 8th then slowly rising to about 16.0 by 19th.